Carbon dioxide (CO2) gas is one of the major greenhouse effect gases and it is said that increase of the carbon dioxide gas in the atmosphere is the cause of the problem of global warming. Thus, investigations are being made for the technologies capable of removing carbon dioxide gas from the atmosphere and also for the technologies capable of processing the removed carbon dioxide gas.
For example, so-called “carbon capture and storage technology” is a promising technology enabling mass removal of carbon dioxide gas emitted from power plants or factories by capturing and burying the same under the seabed for storage or by enabling liquescence or solidification.
On the other hand, a large social impact would be attained if there is realized a technology capable of converting the carbon dioxide gas removed from the air or environment to other form or other compound suitable for storage or capable of reacting with other gases or suitable for supplying to devices such as a fuel cell with low cost.
Further, a hydrogen gas is used these days in various fields including the field of energy such as fuel cells and chemical industries. Conventionally, hydrogen gases have been produced mainly by electrolysis of water or by extraction from natural gases. However, electrolysis of water consumes a large amount of electric energy. Thus, if the technology capable of extracting a hydrogen gas from the water vapor contained in the air with low cost is realized, a large social impact would be attained similarly to the case of the carbon dioxide gas.